Available wireless local area networking technologies such as the Bluetooth technology are widely included in various mobile devices. The devices are typically allocated an IP (Internet Protocol) address and they may communicate with other devices using the IP protocol stack. Besides desktop/laptop computers and mobile terminals, networking technologies are also incorporated to various domestic appliances, such as TV sets, set-top boxes, stereo systems, personal music players, cameras, home management systems and fridges. It is expected that various domestic appliances will be capable of interacting with other devices and sharing information by using especially wireless local area networking technologies and IP-based technologies.
UPnP™ (Universal Plug and Play) technology by UPnP Forum defines an architecture for peer-to-peer network connectivity of intelligent appliances, wireless devices, and personal computers of all form factors. It is designed to bring easy-to-use, flexible, standard-based connectivity to ad-hoc or unmanaged networks whether in the home, in a small business, public spaces, or attached to the Internet. UPnP technology provides a distributed, open networking architecture that leverages TCP/IP (Transport Control Protocol/Internet Protocol) and the Web technologies to enable seamless proximity networking in addition to control and data transfer among networked devices from a wide range of vendors. According to the UPnP Device Architecture (UDA) a device can dynamically join a network, obtain an IP address, convey its capabilities to other devices, and learn about the presence and capabilities of other devices.
The DHWG (Digital Home Working Group) HNv1 (Home Network version 1) specification describes an environment formed by devices like PCs, TV sets, set-top boxes, stereo systems, etc. that are connected to the network via an IEEE 802.x interface including the Ethernet and the wireless local area network WLAN. The devices forming the HNv1 environment are by their nature static or with very limited mobility, allowing them to be always connected to an AC (Alternating Current) power supply. At the same time the connectivity technology they use allows high data rates and low latency.
Constrained devices like mobile phones, PDAs (Personal Digital Assistant), portable music players or cameras are typically not able to support 802.x communication technology, but they often deploy energy saving short-range communication media, such as Bluetooth. Short-range communication media typically exhibits more limited bandwidth and longer delays than an IEEE802.x media. Since these constrained devices or in DHWG terminology mobile handheld devices use different communication media than HNv1 devices, an interworking unit is required. Connecting different networks together as such is commonly used technology, but the architecture of HNv1 exhibits communication environment which is problematic for mobile handheld devices that have limited energy resources and/or slow communication link. HNv1 specifies that the UPnP is used as service discovery and controlling protocol suite, which potentially and in certain conditions may result in a considerable amount of communication for which the device needs to response. More particularly, according to the UPnP discovery protocol the UPnP devices advertise their services to other devices in the system by sending multicast messages. Further, also services and/or interested devices may be searched by multicast requests. The UPnP specification specifies that a UPnP devices should send each advertisement message more than once due to the usage of unreliable UDP (User Datagram Protocol). The result is that the numerous multicast messages will consume the battery of the receiving device within a much shorter time, causing unsatisfactory user experience. Also, in some conditions a considerable amount of the capacity of the connecting link is used for control communication, which prevents the use of the services available.